1. Field of the Invention
The present invention relates to the field of design for manufacturing techniques of devices and process optimization in general. More particularly, the present invention relates to methods and systems for designing devices such as for example integrated circuits and/or electronic circuits and corresponding manufacturing techniques.
2. Description of the Related Technology
Devices, such as integrated circuits and/or electronic circuits, for today's applications need to operate fast, be small and be low power consuming. Often a trade-off between the device speed, the area used and the power consumption is to be made. These metrics put a high burden on the devices that can be used and on their corresponding manufacturing techniques, especially as in view of economic cost the production of such devices needs to have a high production yield. The production yield thereby is specified as the ratio of work to be done to the number of good devices that are produced.
In current manufacturing design applications, the manufacturing technology to be used is fixed first, thus determining the design rules imposed on the designer, leaving only some remaining technology options open. Assuming the fixed manufacturing technology, the designer tunes the device to be obtained to an optimum with respect to the manufacturing yield and area, performance and power metrics after processing based on design component information available from libraries and using the remaining technology options selectable from an available set.
An alternative way to increase yield in device manufacturing that has been exploited is the improvement of the overall variability for the whole library, resulting in a huge optimization process of the library. Reducing the overall variability for the whole library and thus limiting the variability of the constituting subsystems may result in over-design, making the design more sensitive to other sources of yield loss. The overall reduction of variability of the library furthermore is labor-intensive and often implies a trade of between power and yield.
One technique that is often used for guaranteeing that requirements on a given metric, e.g. device speed, are reached by selecting the design components too fast so that it still is fast enough if some of the device components are a bit too slow due to a variation during the manufacturing process of the device components. The latter unfortunately results in a larger power or area consumption for the device. Furthermore, over-design also may result in a reduction of the overall production throughput.
A further technique often used is design for manufacturability (DFM), which is a design methodology using a set of techniques to modify the design of integrated circuits in order to improve e.g. the functional yield, the parametric yield, the reliability, etc. With design for manufacturability techniques, the most critical regions are analyzed and the design is locally changed for increasing the yield. Such techniques include substituting higher yield cells where permitted by timing, power and routability, changing the spacing and width of the interconnect wires where possible, optimizing the amount of redundancy in internal memories, substituting fault tolerant vias in a design where possible, etc.
Although a number of supporting methods have been provided for supporting system design technology, systematic methodologies and appropriate supporting design tools still are required for obtaining a good trade off between design time, economical cost and efficiency of the system.